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From: olaf@cwi.nl (Olaf Weber)
Subject: Re: The Search For Truth
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Date: Mon, 12 Jun 1995 11:34:20 GMT
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In article <Pine.LNX.3.91.950609092302.14087A-100000@linux2.ph.utexas.edu>,
Stephen Froehlich <froehlik@physics.utexas.edu> writes:
> On Fri, 9 Jun 1995, Olaf Weber wrote:

>> Even if you can "introduce free will" in the brain in this manner,
>> there remains the question of how "free will" is produced by the
>> "soul".  And once you begin to look into that, you encounter the same
>> problems as when you try to figure out how the brain could produce
>> "free will".

>> Rather than looking for ways to "introduce free will" into the brain,
>> you should consider taking a principled look at exactly what you think
>> "free will" is, what it can and cannot do.  You might find that even
>> determinism need not be incompatible with it.

> 	It is not so much that we know that Heisenberg fluctuations are a 
> causual as much as we can't seem to find a cause for them, therefore we 
> assume the former.

Well, the theory suggests that they should be there, and they are.
The math used in the theory also suggests that they should have other
properties, like satisfying a certain probability distribution, and
they appear to do this.

I'll call a fluctuation "random", in this context, if the probability
distribution of it happening matches the distribution predicted by the
theory.

A fluctuation is causally underdetermined in the sense that there is a
probability of it occuring within a given region and time-frame, but
no certainty.  To the extent that the fluctuation is underdetermined
it can also be said to have been uncaused if it does occur.

Thus the probability distribution is directly related to the extent to
which the fluctuation is uncaused.  Change the latter, and the former
changes as well.  Conversely, we can say that causation "works" on a
fluctuation by changing the probability distribution.

> We do know that there seems to be no deterministic pattern to these
> events, so if we put a cause behind fluctuations, we can assume that
> they are non-determined and still match experimental data.

We can establish an observed probability distribution (by repeated
observations) and compare it with the expected distribution (derived
from the theory) and compare the two.  A difference indicates that the
theory does not take all causes into account, that the fluctuations
are non-random.

> I get the feeling that patterns of fluctuations that would set off
> various thoughts in the mind would appear random to any physical
> experiment.

Having a neuron "magnify" such fluctuations _is_ a kind of physical
experiment.  And if the fluctuations appear random to the neuron they
occur in then you have nothing but a random nerve pulse generator.

To be useful, in the sense of "intefacing" the soul, the patterns of
fluctuations would have to be non-random.  Otherwise, you can apply
Occam's razor and the cut the soul out of any explanation for our
behaviour.

> All we're doing when we observe these things is basically counting.
> The patterns "look" random, and are for all physical intents and
> purposes.  I truly doubt that this theory is testable.  I can't
> think of any appropiate experiment anyway.  Can you?

Well, it should be obvious now that a test of the theory amounts to
determining the theoretical probability distribution of a (repeatable)
event, and matching it with the observed distribution.

Suppose we know enough of the brain to determine that fluctuation F
has to be "magnified" for a subject to think thought T.  We repeatedly
ask the subject to think T.  He could only do that reliably if he can
influence the probability of F.

A more feasible experiment would involve quantum fluctuations outside
of the brain, on the hope that the ability to influence events in the
brain doesn't stop at its limits.  You take a random number generator
that depends on quantum fluctuations for its functioning, and
calibrate it to produce a certain distribution of random numbers.  The
experiment then consists of seeing if someone can change that
distribution by "wanting" to do so.  (Some parapsychological
experiments are of this form.  The results so far are equivocal at
best.)

> 	What I think free will is is simply the ability to act however
> you choose within your physical limitations.  By however you choose
> I mean an unpredicated decision.  Not wholly unpredicated, but some
> small part is without predicate.

Could you be clearer on the "upredicated" bit, I'm not sure I
understand what you mean.

> 	If this is included in your definition of determinism, then
> fine, I'll probably agree.

I do not think that determinism is incompatible with an ability to
choose, although it might violate some of your intuitions about
choice.

> The brain, though, is not a static system, synapses change over
> time, and those changes and their effects are goverened by the law
> of sensitive dependence on inital conditions.  If there's any place
> where something as small as a quantum fluctiation can be blown up
> into macroscopic effects in a hury, the brain, espically that of a
> human, has to be it.

The brains has to be it, granted, but there is little reason to
believe that the brain actually has this ability.  Neurons seem fairly
impervious to quantum effects.

-- Olaf Weber
